No offence meant to OP, but all of these are so popular that almost everyone knows about them. There wasn't a single app I hadn't heard of, beforehand.
Sent using my S4
All that proves is that you've seen them all, not that "almost everyone" knows about them. I've been using and rooting Android phones since Froyo came out and there were a number of apps on this list that I hadn't heard of and, in all likelihood, will start using frequently from now on (e.g. Appygeek, Digical, Greenify). This list would be priceless to newbies. It also serves as a starting point for discussion so that others can make constructive contributions to fellow XDA members' knowledge. Thanks for taking the time to compile and post them OP.
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My 2c
Kii keyboard. Nice medium between Swype and Swiftkey. Very customisable, accurate, and works well on GS4 and tablets
Network monitor mini pro – leaves a discrete display on your screen (always on or customisable for different apps/contexts) that displays network up and down speeds. Great for tracking if you are leaking data or if a download is finished while you are using another app
Easy uninstaller – Lets you do batch uninstalls. Great if you like experimenting with apps, get a build up, and then feel the need to prune every now and again.